Visual representation of the ELP criteria applied in this study. Depicted are the PFS irradiances of the EVE Fe XX 13.29 nm (blue) and Fe XVI 33.54 nm (green) emission lines for the X1.8 flare on October 23, 2012. The horizontal dotted line represents the pre-flare level. The shaded gray areas correspond to the region in the Fe XVI light curve that satisfies criterion 1 (darker shade of gray) and criterion 2 (lighter and darker shade of gray together) given in Sect. 3.1. The horizontal dashed green line marks the limit corresponding to criterion 3, whereas the horizontal dashed blue line depicts the limit for criterion 4.